All games in fullscreen auto-minimize

I have Windows 7 Home Premium (x64) and every time I try to open a full screen game, it automatically minimizes to the task bar. This happens with every game I attempt to play in full screen.
My video card is a Nvidia Geforce 240

Check which programs are running before you start the game. It might be your antivirus stealing focus from the fullscreen application; or perhaps a download manager, Skype... Basically, anything that can display notifications even when you're running something in full screen.

If the games don't freeze or crash, I doubt it has anything to do with your graphics card or its drivers...

Switch to Basic theme , kill explorer.exe